In recent years, a system has been developed for exchanging information among devices, such as home electric appliances in a home, by connecting these devices via a wireless network. In such a system, for example, a control device and a plurality of electric apparatuses which are communication devices are installed in a home. A wireless network is configured through which these communication devices are connected according to a star topology having the control apparatus at the center. Examples of these communication devices include, for example, a TV, an air conditioner, a refrigerator, a washing machine, and a mobile phone.
In such a configuration, depending on an installation status of a communication device, reception intensity of electric waves from other communication devices (communication partner devices) decreases significantly to the point of being null due to multipath propagation in some cases.
Even when the reception intensity of the electric waves decreases to the point of being null, if the communication device is a portable apparatus (movable object) such as a mobile phone, propagation of the electric waves changes as the communication device moves. Thus, the communication device can recover from null of the reception intensity of electric waves, whereby communication succeeds with a communication partner device.
Furthermore, a technique is disclosed which allows two communication devices to communicate with each other even when the communication devices are being moved, by controlling the direction of directional antennas in accordance with a position relationship between the two communication devices (see Patent Literature (PTL) 1, for example).